BCGControlBar Pro for MFC
BOOL CBCGPToolbarButton::IsVisible ( ) const
inline

Determines whether a toolbar button is visible or not.

Returns
Nonzero if a toolbar button is visible; otherwise 0.

You can show or hide toolbar buttons using SetVisible(). It's recommended to call CBCGPControlBar::AdjustSizeImmediate when you have finished with calls on SetVisible().